[PATCH] add the bus name to the hotplug environment

Add the name of the bus and the driver to the hotplug event for
/sys/devices/*. With this addition, userspace knows what it can
expect from sysfs to show up, instead of waiting for a timeout
for devices without a bus.

  ACTION=add
  DEVPATH=/devices/pci0000:00/0000:00:1d.1/usb3/3-1
  SUBSYSTEM=usb
  SEQNUM=978
  PHYSDEVBUS=usb
  PHYSDEVDRIVER=usb
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/base/bus.c

@@ -247,7 +247,7 @@ int bus_for_each_drv(struct bus_type * bus, struct device_driver * start,
  *	device_bind_driver - bind a driver to one device.
  *	@dev:	device.
  *
- *	Allow manual attachment of a driver to a deivce.
+ *	Allow manual attachment of a driver to a device.
  *	Caller must have already set @dev->driver.
  *
  *	Note that this does not modify the bus reference count

drivers/base/core.c

@@ -116,8 +116,29 @@ static int dev_hotplug(struct kset *kset, struct kobject *kobj, char **envp,
 			int num_envp, char *buffer, int buffer_size)
 {
 	struct device *dev = to_dev(kobj);
+	int i = 0;
+	int length = 0;
 	int retval = 0;
 
+	/* add bus name of physical device */
+	if (dev->bus)
+		add_hotplug_env_var(envp, num_envp, &i,
+				    buffer, buffer_size, &length,
+				    "PHYSDEVBUS=%s", dev->bus->name);
+
+	/* add driver name of physical device */
+	if (dev->driver)
+		add_hotplug_env_var(envp, num_envp, &i,
+				    buffer, buffer_size, &length,
+				    "PHYSDEVDRIVER=%s", dev->driver->name);
+
+	/* terminate, set to next free slot, shrink available space */
+	envp[i] = NULL;
+	envp = &envp[i];
+	num_envp -= i;
+	buffer = &buffer[length];
+	buffer_size -= length;
+
 	if (dev->bus->hotplug) {
 		/* have the bus specific function add its stuff */
 		retval = dev->bus->hotplug (dev, envp, num_envp, buffer, buffer_size);